Oc Motility

Front 1

The purpose of a pursuit is to

Back 1

Maintain object of regard on the fovea

Front 2

A saccade functions to

Back 2

Place the object of regard on the fovea rapidly

Front 3

The vergence system functions to

Back 3

Align the visual axes to maintain bifoveal fixation

Front 5

Fast muscle fibers have

Back 5

Single motor endplates – impulse results in twitch

Front 6

Slow muscle fibers have

Back 6

Multiple nerve endings (en grappe) – graded contractions in the absence of muscle action potentials

Front 7

The longest EOMs are the

Back 7

Horizontal recti

Front 8

The thickest EOM is the

Back 8

Medial rectus

Front 9

The thinnest EOM is the

Back 9

Lateral rectus

Front 10

Hering’s law states that

Back 10

Two yokes muscles are equally innervated

Front 11

Vertical movements are around the

Back 11

X axis

Front 12

Horizontal movements are around the

Back 12

Z axis

Front 13

Torsional movements are around the

Back 13

Y axis

Front 14

Sherrington’s law of reciprocal innervation:

Back 14

When agonists stimulated, antagonists are inhibited

Front 15

Vestibular ocular reflex (VOR) functions to

Back 15

Allow eyes to fixate on an object despite head movement

Front 16

The stimulus to VOR is

Back 16

Movement of semicircular canals – 3 neuron arc

Front 17

VOR is faster than the pursuit system

Back 17

Can track up to 4 HZ –

Front 18

VOR latency =

Back 18

15msec

Front 19

Microsaccades are

Back 19

Moderately rapid eye movements (2-10deg/sec) 1’-25’ of arc and durations up to 25msec

Front 20

Microtremors occur at

Back 20

High frequency (70HZ) – small amplitude

Front 21

Microdrifts are composed of

Back 21

Smooth pursuit, vergence and VOR eye movements (slow)

Front 22

A version is a movement when

Back 22

The lines of site maintain the same visual angle

Front 23

Rightward looking is called

Back 23

Dextroversion

Front 24

Leftward looking is called

Back 24

Levoversion

Front 25

Rotation rightward is called

Back 25

Dextrocycloversion

Front 26

Rotation leftward is called

Back 26

levocycloversion

Front 27

Smooth pursuits are a

Back 27

Sloe, steady, involuntary movement that is mediated by a graded response – constant velocity - ~40 deg arc/sec

Front 28

Latency of smooth pursuits =

Back 28

125msec

Front 29

Saccades are

Back 29

Very rapid eye movements – may reach 1000deg arc/sec – initiated by a burst of nerve impulses

Front 30

Latency of saccades =

Back 30

120-160msec

Front 31

Dynamic overshoots are

Back 31

A consequence of multiple pulse saccadic movements

Front 32

Vergence movements have a maximum velocity of

Back 32

~21 deg arc/sec (slow)

Front 33

The latency for vergence eye movements is

Back 33

160msec (twice as fast as that for accommodation)

Front 34

A dynamic overshoot are present in

Back 34

Convergence and accommodation – not divergence

Front 35

Caloric testing for internuclear ophthalmoplegia

Back 35

COWS cold opposite warm same (pontine gaze mechanism)

Front 36

Spasmus nutans

Back 36

- Presents during the first year of life- lasts several months – spontaneously resolves- nystagmus is fine, pendular and rapid- associated with strabismus

Front 37

Optokinetic nystagmus (OKN)

Back 37

Induced nystagmus – not dependent on good VA – manifestation of fixation

Front 38

The most common clinical use of OKN is in the

Back 38

Diagnosis of parietal lobe disease (disturbance of OKN response in disease affecting the optic radiations)

Front 39

Blinking proceeds in a

Back 39

Lateral to medial direction, wiping the cornea clean